"""搜索建议 - 真实文章标题片段表(articles 写入 trigger 自动维护)。

- 数据源:articles.title_zh(优先)/ articles.title(短新闻回退)
- 用途:/api/v1/search/suggestions 返回"真实文章标题"建议(B 方案)
- 维护:PG trigger(articles INSERT/UPDATE OF title_zh/title/published_at 触发)
- 查询:prefix_keys @> ARRAY['美'] 走 GIN 索引,按 published_at DESC 排序
"""
from __future__ import annotations

from datetime import datetime

from sqlalchemy import BigInteger, DateTime, ForeignKey, String, func
from sqlalchemy.dialects.postgresql import ARRAY, TEXT
from sqlalchemy.orm import Mapped, mapped_column

from app.database import Base


class SearchTitleSuggestion(Base):
    __tablename__ = "search_title_suggestions"

    id: Mapped[int] = mapped_column(BigInteger, primary_key=True)

    article_id: Mapped[int] = mapped_column(
        BigInteger,
        ForeignKey("articles.id", ondelete="CASCADE"),
        nullable=False,
    )

    # 该条用的是哪边的文本:'zh' (title_zh) / 'src' (title 短新闻回退)
    title_lang: Mapped[str] = mapped_column(String(8), nullable=False, default="zh")

    # 预计算前缀数组(从第 1 字到全词)
    prefix_keys: Mapped[list[str]] = mapped_column(ARRAY(TEXT), nullable=False)

    published_at: Mapped[datetime | None] = mapped_column(DateTime(timezone=True))

    created_at: Mapped[datetime] = mapped_column(
        DateTime(timezone=True), server_default=func.now(), nullable=False
    )

    def __repr__(self) -> str:
        return f"<SearchTitleSuggestion article_id={self.article_id} lang={self.title_lang}>"